Windows WLAN Service: Denial of service through integer underflow
Summary
An integer underflow in the Windows WLAN Service of Windows 11 and Windows Server 2025 allows an unauthenticated attacker to cause a denial of service over the network. The record states only an availability impact, with no confidentiality or integrity impact. The record does not say whether the attack must come from the same Wi-Fi radio segment, so reachability on wired-only hosts is unknown.
Affected
- Windows 11 Version 23H2: 10.0.22631.0 to before 10.0.22631.7652
- Windows 11 Version 24H2: 10.0.26100.0 to before 10.0.26100.9711
- Windows 11 Version 25H2: 10.0.26200.0 to before 10.0.26200.9711
- Windows 11 Version 26H1: 10.0.28000.0 to before 10.0.28000.3231
- Windows 11 Version 26H2: 10.0.26300.0 to before 10.0.26300.9711
- Windows Server 2025 (including Server Core): 10.0.26100.0 to before 10.0.26100.33650
- Note: the NVD CPE lists only Windows 11 23H2; the version list above comes from the CNA record and has not been verified on MSRC.
Fixed in
- Windows 11 Version 23H2: 10.0.22631.7652 or later (related update KB5126653, to be verified)
- Windows 11 Version 24H2: 10.0.26100.9711 or later
- Windows 11 Version 25H2: 10.0.26200.9711 or later
- Windows 11 Version 26H1: 10.0.28000.3231 or later
- Windows 11 Version 26H2: 10.0.26300.9711 or later
- Windows Server 2025: 10.0.26100.33650 or later (related update KB5126646, to be verified)
- Build numbers and KB numbers must be checked on the MSRC Security Update Guide before rollout.
Workaround
Unknown.
Exploitation
- Not listed in CISA KEV.
- CISA SSVC: exploitation none, automatable yes, technical impact partial.
- EPSS approximately 1.2%.
- No public proof of concept or in-the-wild exploitation found in the sources.
Our recommendation
- Install the October 2026 security update on affected Windows 11 clients and Windows Server 2025 systems in the normal monthly update cycle.
- Prioritise servers and Wi-Fi-enabled laptops.
- Verify the build numbers and KB articles on the MSRC Security Update Guide before deployment.
- Check whether WLAN-capable endpoints and servers are reachable from untrusted network segments and restrict access where possible.
- Monitor for unexplained service outages or crashes of the WLAN service.
Information from Microsoft (Patch Tuesday October 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-83855 msrc.microsoft.com
- OpenCVE: CVE-2026-83855 app.opencve.io
- Vulners: CVE-2026-83855 vulners.com
- Vulners (Rapid7): Windows CVE-2026-83855 vulners.com
- Strix: CVE-2026-83855 www.strix.ai
- Microsoft partner CVE list 2026 (PDF) cdn-dynmedia-1.microsoft.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 2 Nov 2026, 18:43.
Original description (NVD)
Integer underflow (wrap or wraparound) in Windows WLAN Service allows an unauthorized attacker to deny service over a network.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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